1. Field of the Invention
The invention relates to an optical device, particularly to a controllable optical device.
2. Description of the Prior Art
The liquid crystal lens or liquid lens is composed of liquid crystal polymer mixture or oil and water mixture. The arrangement of these fluids will be changed in accordance with the change of electrical field distribution. This property is utilized by the optical device to focus or diverge the light beam.
The conventional optical focus-changing lens set needs at least two lenses to obtain the focus-changing effect. The shortcoming of the method is that it is heavier and larger than current optical focus-changing lens set.
In addition, in order to obtain the required phase retardation effect, the liquid crystal lens usually needs thicker liquid crystal layer. However, thicker liquid crystal layer will cause longer response time. For example, if the liquid crystal layer is 60 μm thick, its response time will be about 30 seconds, and operation voltage will be greater than 30 voltages.
In the prior art, the overdrive way has been used to operate the liquid crystal display, in order to improve the focusing time of liquid crystal. However, it needs extra circuit for overdrive, thus it becomes a burden for the cost.
The liquid lens mainly controls the position and distribution of oil and water in the box to form light focusing or light diverging device. However it has to overcome the viscous force and need larger voltage. In addition, if the operation voltage is not large enough, the response speed will be very slow.
Therefore, in order to produce more effective liquid lens, provide better production technology to the industry, it is necessary to research and develop the innovative liquid lens, so as to increase the production efficiency of liquid lens and reduce the manufacturing cost.